| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC/DC converter of higher energy conversion efficiency by reducing the switching frequency of a switching element at a low load, resulting in a reduced switching loss. SOLUTION: An IC circuit 100 for controlling a switching power source comprises a reference voltage circuit 10 which generates a reference voltage value Vref for a detection voltage signal Vo, a reference voltage circuit 21 for generating a reference voltage value Vref_lmt which is lower than the reference voltage value Vref, an operational amplifier 11 which outputs an error voltage between the detection voltage signal Vo and the reference voltage value Vref, and an oscillator 12 which generates a triangular wave voltage signal at a constant frequency. It further comprises a comparator 13 for comparing the error voltage with the triangular wave voltage signal, a comparator 22 for comparing the detection voltage signal Vo with the reference voltage value Vref_lmt, and a comparator 31 for setting a hysteresis voltage in which the upper limit value and lower limit value of a load current IL that flows an inductor L are a voltage upper limit value Vc_H and a voltage lower limit value Vc_L. COPYRIGHT: (C)2005,JPO&NCIPI
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